Articulating work machines, such as scrapers, wheel loaders, and trucks, generally include a front frame structure and a rear frame structure which pivot relative to one another in order to steer the work machine during operation thereof. Typically, a number of fluid cylinders are secured at one end to the front frame structure, and at a second end to the rear frame structure. Such fluid cylinders are generally operator controlled hydraulic cylinders in which selective extension and retraction thereof cause the front frame structure to pivot relative the rear frame structure thereby allowing the operator to steer the work machine during advancement thereof.
Moreover, a number of fluid-powered differential assemblies have heretofore been designed for steering an articulating work machine. Use of such fluid-powered differential assemblies is advantageous in that power may be continuously supplied to the wheels of the articulating work machine during articulation thereof. Such an advantage is not present in a number of work machine designs utilizing only hydraulic cylinder articulation arrangements.
It would be desirable to provide a steering control system for an articulating work machine which controls both a number of steering fluid cylinders along with a fluid-powered differential assembly. Moreover, what is further needed is such a steering control system which includes a backup system for steering the articulating work machine in the unlikely event of a hydraulic power failure.